1. Field of the Invention
The invention relates to a magnetic sensor for an elevating motor, and more particularly to a magnetic sensor whose magnetic induction elements are sealed within a magnetically non-permeable minor sleeve. Meanwhile, a signal transmission line is extended therefrom. In addition, the minor sleeve and the magnetic induction elements are disposed within a gear box of the elevating motor.
2. Description of the Related Art
There are a great number of motors that are differently designed according to different requirements. As shown in FIG. 1, an elevating motor 10 applied to the treadmill substantially includes a gear box 11 in which a transmission gear (not shown) is disposed. A motor 12 is employed for supplying power to the transmission gear that enables a threaded rod 14 to retract or extend axially in a sleeve 13. In this way, the elevating motor 10 is utilized for adjusting the inclination of a platform 20 relative to a base frame 30. In other words, the tilt angle of the platform 20 is adjustable to meet different requirements of the operators on the tilt angle of the platform 20. In order to control the tilt angle of the platform 20, it is quite normal to install a sensor (not shown) for detecting the tilt angle of the platform 20 at a certain place of the treadmill 40. Accordingly, the change of the driving motion of the elevating motor 10 is measured and controlled for adjusting the tilt angle of the platform 20. However, this conventional elevating motor 10 requires a sensor positioned outside to provide the measuring signals of the driving motion change thereof, thereby controlling the driving state.
Nevertheless, the conventional sensor of the driving motion change is disposed at the external side of the elevating motor 10. It will take much time and cause difficulties in assembly. Moreover, the detection will be easily affected by the external environment, thereby reducing the accuracy. In addition, the structure will be easily damaged as well so that the service life is much lowered. Thus, these problems require further improvements.
According to the prior art, it is also quite normal to install a magnetic sensor between the rotor and the stator of the motor for detecting the speed of the rotor. The detection results are used for an accurate control. However, the structure of the elevating motor is different from that of the normal motor. Therefore, it is not easy to secure it to the inside of the gear box of the transmission mechanism. Therefore, there are still many problems to be overcome.